The present invention relates to a semiconductor device such as a solid-state imager and a delay line having imager elements and/or charge transfer elements.
A solid-state imager, for example, of CCD (charge coupled device), CPD (charge priming device), CSD (charge sweep device), and MOS type has an imager body made up of imager elements and a shift register. The imager body is adapted such that signal charges are generated by the imager elements responding to received light according to a picked up optical image and the signal charges are transferred by the shift register to be delivered from an output terminal.
In such a solid-state imager, there is provided a peripheral circuit including such as a drive circuit providing clock signals and the like for driving the solid-state imager body, i.e., the imager elements and the shift register receiving the signal charges therefrom so as to transfer the same, and a signal processing circuit.
Conventionally, such a device, in general, has been formed on separate semiconductor chips, the imager body on one chip and the peripheral circuit on another.
However, with the recent demand for miniaturized and simplified layout of solid-state imagers and for mass producibility of the same, there is a tendency toward incorporating a peripheral circuit such as the drive circuit with the solid-state imager body including the aforesaid imager elements, shift register, and the like, and disposing them on one common semiconductor chip.
In the case of a linear sensor with the aforesaid arrangement wherein the imager elements are linearly disposed, for example, as shown in FIG. 2, a plurality of imager elements 1 are arranged in a line on a semiconductor chip 4 with a pair of shift registers 2 disposed on their both sides, each thereof taking in the signal charges, for example, from every other one of the imager elements 1 corresponding to the light quantities received thereby, for transferring the same, and on the semiconductor chip 4 with the body of the device 3 made up of such imager elements 1 and shift registers 2 disposed thereon, there is also disposed a peripheral circuit 5 including, for example, a timing generator 6, drive circuit 7, and the like. Since, however, the quantity of heat generated by the transistors forming the drive circuit 7 is rather large, it produces problems especially with a linear sensor as shown in the drawing having the imager elements and shift registers distributed over a considerably elongated space. That is, there are produced remarkably large temperature differences between the portion where the drive circuit 7 is disposed and portions spaced apart therefrom, and therefore, considerable unevenness occurs in the thermally generated electric charges, i.e., in the dark currents. The influence of the unevenness in the dark currents is especially serious on such a device as described above treating analog signals, that is, uneven contrast, for example, is produced by the imager of the aforesaid type.